The timid invasion

SUMMARY In biological invasion processes animal behavior moderates the success of invasive species, and the native fauna’s ability to adapt. The importance of behavioral syndromes and flexibility of invading species for invasion success remains debated. We investigated behavior of rodents, the bank vole ( Myodes glareolus ) currently invading Ireland, and the native wood mouse ( Apodemus sylvaticus ) that declines with vole invasion, at replicated sites at pre-invasion, edge, and source of the invasion. We found that individual rodents varied consistently in risk-taking behaviors, and mice had not adapted to the presence of invasive voles. Voles at the invasion edge were more careful but also more flexible compared to voles the invasion source. The ability to develop timid and flexible phenotypes may contribute to the invasion success of rodents worldwide.